This is an issue for us too. It’s bigger than just error logs… we’ve been getting random 404s on some of our websites wp-admin/plugins.php pages. There is no log trail anywhere other than this error that you reported. Then when I disable the user-photo plugin, we don’t get the 404s anymore on our wp-admin/plugins.php page. Really weird and I am not sure if this is even the real culprit but it’s something I need to get resolved so I can rule it out.
Any idea on when developers can get this resolved? We love this plugin.